JonW

Most people seem to agree that their car runs better with a CAI and a tune. But it seems to me that the tune is responsible for most of that performance gain. However, do the CAIs have a larger MAF than stock? Is this also a part of the performance gain. I can't see how just the conical air filter alone is responsible for the gain.

Also, if I modify my stock air box to flow more air, am I going to get a CEL if I start running too lean?

spike

I believe the tune account for 2/3 of the gains and the MAF accounts for 1/3 of the gain. The reason to get them together is you usually can get quite a deal if you buy a tune/tuner/CAI together as a package. There are some "tuneless" CAIs but the gains aren't great unless you get a tune with it. However, if you buy a CAI that does require a tune you MUST get a tune or risk throwing codes. I don't know about modifying the stock airbox but that seams like a bad idea without tuning.

karman

I have one of the more restrictive CAIs (K&N), but I dyno tested every step.
CAI=4HP
CAI & custom tune 12HP.
A JLT or C&L with a tune will yield a little more HP because they have more air flow.

GT John

Here ya go. You may want to read this.

http://www.mustang50magazine.com/tec...e_comparisons/

AWESOMO 4000

The big thing, in an anything-other-than-a-supercharged-state, keep the MAF size around 90mm. Anything larger is a waste. It's a 300hp car, not a 1000hp car.

TacoBill

Mine's a 95mm. Guess it's a waste.

GT Bob

The reason that these cars need a tune with the aftermarket intakes is that you are increasing the MAF size. By switching the MAF size, your increasing the amount of air that the engine is getting. However, without updating the information that the computer has in it, it has no idea that you did this and only adds fuel for the amount of air it knows about. Then, the O2 sees that its running lean, and tells the COmputer to add more fuel to compensate, which it will, but only to a certain point. It eventually reaches a point where the computer says, "Ok, something is wrong. I have added as much fuel as I am allowed to, and things are still too lean." Thats when it throws the check engine light.

The tune fixes this by updating the computer so it knows that it's MAF is larger. Once it knows this, it can adjust the fuel as needed. Now, most tunes go beyond that and update fuel ratio's, timing, cam phasing, and shift points (if you have a slush box tranny).

Saying one will net ya X HP and the other Y HP is simply wrong... No mod lives in a vaccum. One mod, helps the next, and helps the next. So an intake alone may add 5 HP and a tune will also add 5, but together, they likely add 12.

The other thing to remember is that the intake and exhaust (which you really HAVE to think about as one long path, because thats what it is) will only flow as well as the most restrictive part. IMO, the most restrictive from the factory is the MAF, and the second are the Exhaust Manifolds... and Bill, you haven't wasted your MAF.. your just extra prepared for more exhaust work

TacoBill

Welcome to TMS Bob!

Quite the 1st post I must say.

With my O/R-H and Stingers, I'd say my rear end is breathing pretty good.

don_w

Aaaa.... you're just getting started. You still need LTs, ported heads, cutouts... hahah

Rash

Okay, dumb question, but when you say things like "keep the MAF at 90 mm", are you referring to the throttle body size? Cause the MAF sensor is just one size and isn't changeable, correct?

TacoBill

Trying to get me in trouble, Don?

Bad enough I got to swap back in some OEM stuff for smog (in 2011), but to hassle with LT's back and forth..

MrClean

+1...and on top of that, until I'm out fo warranty (at which point I'm confident any "issues" with the engine would have surfaced), I'm keeping the stock exhaust manifolds and cats...

MrClean

1. there are no dumb questions...
2. the MAF size referres to the cylindrical piece that houses the MAF sensor...so in an OEM airbox its made of plastic and it's 90 mm (I think), and in C&L Racer it's made of aluminum, and it's 95mm. When you install the C&L Racer, you pull out the sensor from the OEM MAF housing and install it into the C&L aluminum MAF housing..

m05fastbackGT

You're right on the money, except for the stock MAF ! which is 80mm in diameter, not 90mm..Only the Steeda MAF ! is 90mm, followed by the JLT at 88mm, and C&L street CAI at 83mm. Both the Demolet TI and C&L racer MAF are 95mm, however the Airaid has the largest MAF at 98mm.

Rash

Thanks for clearing that up. You'd think I'd know since I just installed a JLT CAI.

m05fastbackGT

He's referring to the MAF housing, in which the MAF sensor is inserted..What he's also saying, is that anything larger than 90mm in diameter ? is both a waste and considered as overkill, as the stock 4.6 in naturally aspirated form, can't produce any further power, beyond it's intake airflow capacity..Therefore ! 90mm and lower, are best suited for N/A applications.. While on the other hand ? 90mm and higher ! are best recommened for forced induction, or highly modified applications..

m05fastbackGT

Hey there Bob welcome to TMS.. After reading you're post ! I agree that most of what you posted, is pretty much right on the money..However ! what you posted concerning the stock manifolds, and MAF as being the most restricted ? is absolutely incorrect..First of all, it's not the MAF itself that's restrictive ! it's the stock airbox which is restrictive, by choking off airflow to the throttle body..And second ! it's been proven on the dyno, by Brenspeed, Alternative Auto, and Anderson Ford Motorsport, that the stock exhaust along with the exhaust manifolds, are considered as factory high-flow components, and are very low restrictive when compared with the previous SN-95 model..As a matter of fact ! there's very little to be gained, by swapping out the stock mainfolds in favor of shorty headers ? as they've only been proven to provide a 2-4 HP gain..In addition, according to Brenspeed's test results ! their off road H-pipe, provided no more than 8-10 peak HP, over the stock mid pipe w/cats..The only real benefit, in swapping out the factory exhaust ? would be in favor of Long Tube headers, along with either an off road or high-flow catted mid pipe..Other than that ! you're pretty much wasting both your time, and money IMHO

TacoBill

Performance wise, yes.

But, you're missing the #1 reason why people change their axle-backs and switch out their factory midpipes in favor of an O/R pipe... the sound. That IMO, is worth the time and money.

Rash

One more post to 5000 Bill.

70MACH1OWNER

Bill is spot on once again!!!!! Sound!!! That was my only reason for changing exhaust systems. Bring on the big 5KKKK! Bill
Scott